Conversion of compounds of the acetylene series



Patented Aug. 6,

UNITED STATES PATENT. ori-"icr:

CONVERSION or COMPOUNDS or ran l cn'rmrm spams I Albert Auerhalm, Neckargemuend, and Robert Stadler, Heidelberg, Germany, assignors to I. G. Farbenindustrie Aktiengesellschait, Frankfort-on-the-Main, Germany No Drawing. Application April 26, 1938, Serial No. 204,462. In Germany May 11, 1937 8 Claims.

We have now found that compounds the acetylene series can be converted into compounds of the ethylene series in a considerably more advantageous manner and with very good yields by treating compounds of the acetylene series with aqueous suspensions of zinc'dust which has been activated by treating same with aqueous solutions bi copper and cadmium salts.

The said zinc dust may be obtained for example 20 by introducing powdered zinc into an aqueous solution of a copper salt and then, after the precipitation of the desired amount of copper, further treating with a solution of a cadmium salt.

The solutions'of copper and cadmium salts may 25 also be allowed to act on the zinc powder simultaneously. The hydrogenation may also be carried out by means of a suspension of zinc dust in an aqueous solution of a copper nd cadmium salt. The presence of the said th e metals is es- 3o sential in all cases,- but other metals may be manner, the conversion of the acetylene linkage.

into the ethylene linkage proceeds at leastjfour 40 times as rapidly as when using zinc dust which has been activated with copper alone. Contrary to expectation, only relatively small amounts of .hydrogen are formed in the hydrogenation according to the present process, so that the util- 5 ization of the zinc is very favorable. Moreover,

the hydrogenation of the acetylene linkage proceeds only to the formation of the ethylene linkage without any appreciable formation of the corresponding saturated compounds. Even when 50 acetylene compounds which contain oleflnic double linkages in additionto the triple linkages are hydrogenated, the hydrogenation is limited to the triple linkages. The present invention, therefore, can most advantageously be used for 55 the conversion of vinylacetylene into butadiene.

Inert gases, as for example nitrogen or carbon dioxide, may be present during the hydrogenation. Solvents, especially those having solvent power for acetylene hydrocarbons and not being attacked under reaction conditions, such as the 5 alcohols, may also be added to the suspensions. The co-employment oi dispersion agents or stabilizers, as for example Turkey red oil, alkylated naphthalene sulphonic acids, sulphonates of high molecular weight alcohols, addition products of a plurality of molecular proportions oi.

ethylene oxide to high molecular weight alcohols,

or the fatty acid amides of taurine, has proved advantageous in order to produce the most intimate possible contact between the reactants. The temperature and the pressure may be varied within wide limits, but the reaction proceeds to good results even at ordinary or slightly elevated temperature, e. g., from 40 to 100 C. and at atmospheric pressure. The process may be carried out in an uninterrupted manner or continuously and also in a cycle. In the latter case it is preferable to separate the constituents of the acetylene compound already hydrogenated before repeated leading into the reaction vessel, for example by washing out, condensation and fractional distillation.

The following examples will further illustrate how the said invention may be canied out in practice, but the invention is not restricted tof these examples Example 1 20 grams of zinc dust are shaken for a short time with dilute hydrochloric acid and then washed. The still moist zinc dust is shaken with a solution 01 20 grams of copper sulphate and 4 rams of cadmium chloride in 200 cubic centimeters or water for from 5 to 10 minutes and 40 washed several times with water. The zinc dust treated in the said manner is shaken for half an hour at 50 C. in a vessel containing 150 cubic centimeters of water and 500 cubic centimeters ofacetylene. Within'the said time 84 per cent of the acetylene is converted intoethylene. Ifhe gas obtained contains only 2 per cent of hydro-' gen. v When working in the same manner, but with a zinc powder containing copper alone but no cadmium, there are obtained within the same time only 5.8 per cent 01' ethylene together with 8.5 per cent 0! hydrogen, while'83.3 per cent of acetylene remain unconverted.

' Eoample 2 at a temperature between 40 and 70 C. After an hour, 69.1 per cent of the vinyl acetylene is converted into butadiene. Only 6 per cent of the hydrogen formed are not used 10*. the hydro- I genation.

A zinc dust which has been treated only with copper yields only 12 per cent of butadiene under otherwise identical conditions.

Example 3 A zinc powder treated as described in Example 2 is shaken with 10 liters of gaseous vinyl acetylene and 500 cubic centimeters of water to which 2 cubic centimeters of Turkey red oil have been added for an hour at from to C. The gas contains 71.2 per cent'of butadiene, no hydrogen and no methane hydrocarbons,

Example 4 20 grams or zinc powder treated in the manner described in Example 1 with 20 grams of copper sulphate and 4 grams of cadmium chloride are added to 465grams oi phenyla'cetylene and 300 cubic centimeters of water. The whole is heatedat 50 C. for about one hour in a vessel while stirring. Within this time, the phenylacetylene is converted into styrene except small traces 7 40 thereof.

By working in the same mannen'hut with azinc copper powder containing no cadmium, 52 per v of water and 0.2 gram of the sodium salt oi oleic cent of the phenylacetylene are not at all con verted within the same .time.

Example 5 150 grams of zinc dust are treated in the manner described in Example 2 with copper sulphate and cadmium chloride; 'The zinc dust thus pretreated is admixed with 1500 cubic centimeters acid tauride are filled into a vertical glass tube having a diameter of millimeters. 12 liters of vinylacetylene are bubbled through this mixture in a cycle, thus causing the temperature to exceed 40? C. In the course of 1% hours 84.2 per 15 cent of the vinylacetylene are thus converted into butadiene. The formation of hydrogen does not exceed 2 per cent of the resulting gases.

What we claim is: v

1. A process for the conversion of compounds of the acetylene series into those of the ethylene series which consists in treating compounds of the acetylene series with an aqueous suspension of zinc dusts which has been activated by treating same with aqueous solutions of copper and cadmium salts.

2. A process for the conversion of compounds of the acetylene series into those of the ethylene series which consists in treating compounds of the acetylene series at from 30 to C. with 30 'an aqueous suspension of zinc dust which has been activated by treating same with aqueous solutions of copper and cadmium salts.

3. A process forthe conversion of vinylacetylene into butadiene which consists in-treating 35 vinylacetylene at from 30 to 90 C. with an aqueous suspension of zinc dust which. has been activated by treating same with aqueous solutions of copper and cadmium salts.

r ALBERT sunnusmz.

ROBERT STADLER. 

